FBI Director James Comey has expressed serious concerns about pending legislation that would require “national security officials to certify whether an approved refugee to the United States” should be allowed to enter.

That’s according to CNN’s justice reporter Evan Perez.

“He has some really grave concerns that this legislation would allow anyone, any refugees” into America, Perez told CNN’s Wolf Blitzer on Thursday.

Additionally, Perez noted that Comey has expressed his concerns to both the Obama administration and Congress that, “this requirement, where he would have to personally sign off on every individual refugee coming from Syria and Iraq is just frankly impossible.”